16-bit wchar_t on Windows and Cygwin
Bruno Haible
bruno@clisp.org
Thu Feb 3 10:48:00 GMT 2011
Corinna Vinschen wrote:
> isn't wwchar_t equivalent to wint_t on all
> platforms? On UCS-4 platforms sizeof(wint_t) == sizeof(wchar_t) == 4
> because there's no reason to make it bigger. On UCS-2 and UTF-16
> platforms sizeof(wint_t) == 4 because it must be able to hold EOF as
> well. So, why not just use the wint_t type for the time being?
The "must be able to hold WEOF as well" argument holds for the argument
type of iswwalpha. If we were to call it 'wwint_t', it would be the same as
'wint_t', yes. For this reason, we don't need a separate type 'wwint_t'.
But 'wwchar_t' is the base type for wide wide character _arrays_.
Such arrays don't need to hold the WEOF value. On AIX platforms, where
wchar_t[] is the UCS-2 encoding, wwchar_t[] can be synonymous to it.
There is no need to make wwchar_t 32 bits wide on these platforms.
So, my current code looks like this:
# if (defined _WIN32 || defined __WIN32__) || defined __CYGWIN__
/* Define 'wwchar_t' as a type that
- can hold 32 bits, unlike wchar_t which can hold only 16 bits,
- promotes to 'wint_t' under the default argument promotions. */
typedef wint_t wwchar_t; /* actually 'unsigned int' or 'uint32_t' */
# else
typedef wchar_t wwchar_t;
# endif
Bruno
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